Method of catalytic dehydrofluorination



Oct. 9, 1951 J. F. EBERLE METHOD OF CATALYTIC DEHYDROFLUORINATION 2 Sheets-Sheet 2 Filed Jan. 4, 1949 FIG. 3

INVENTOR- J F EBERLE Ma da- MW ATTORNEYS Patented Oct. 9, 1951 METHOD OF CATALYTIC DEHYDRO- FLUORINATION Jack F. Eberle, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application January 11 Claims.

This invention relates to novel catalysts and processes using same. The invention also relates to methods of preparing catalysts. In one embodiment the invention relates to the removal of organically combined fluorine from hydrocarbon or other organic material. In a more specific embodiment, it relates to the removal of organically combined fluorine from a hydrocarbon eiiiuent of an alkylation process in which a fluorine-containing catalyst is employed. In one aspect the invention relates to the conversion of organic fluorine compounds to hydrogen fluoride and the corresponding organic residue. The invention further relates to the recovery of hydrogen fluoride liberated by such reaction.

In the manufacture of hydrocarbons by processes in which a fluorine-containing catalyst is used, small proportions of organic fluorine-containing by-products are formed. These processes may involve such reactions as polymerization, isomerization and alkylation of relatively lowboiling hydrocarbons to produce motor fuel having a high octane rating, and are effected in the presence of catalysts comprising one or more of such inorganic fluorine compounds as hydrofluoric acid, boron trifluoride and the like. Although the exact nature or composition of these organic fluorine-containing by-products has not been definitely established, they are believed to be predominately alkyl fluorides and/or aryl fluorides. These fluorides are not completely removed by washing the hydrocarbon mixtures in which they are contained with alkaline solutions such as aqueous solutions of sodium hydroxide or sodium carbonate. For the most part, these organic fluorine compounds have boiling points which are not substantially higher than the several reactants used in the conversion process. However, some of the organic fluorine compounds do have higher boiling points than the reactants and the boiling points of the higher-boiling fluorides correspond to the boiling points of the conversion products. As a result, these organic fluorine compounds will be found in the variou hydrocarbon fractions in subsequent separation processes for separating and refining the products, and in many instances the organic fluorine compounds tend to accumulate in the high-boiling hydrocarbon fractions. These fluorides tend to decompose at elevated temperatures, such as those employed in fractional distillation of the hydrocarbon mixture, thereby forming hydro- 4, 1949, Serial No. 69,113 (Cl. 260-683.4)

fluoric acid which is corrosive, especially in the presence of moisture. In gaseous mixtures of hydrocarbons they may thus cause corrosion of treating equipment; in liquid hydrocarbon mixtures, and especially motor fuels, they are undesirable for similar reasons that are obvious and because they reducethe antiknock value of the fuel.

Consequently, it is highly desirable and often essential to minimize the accumulation of the organic fluorine compounds, or to remove them from the hydrocarbon effluent of such processes as described. Various methods have been used to remove the organic fluorine compounds from the hydrocarbon eflluent. For-example, in the alkylation of low-boiling paraflins in the presence of a hydrofluoric acid alkylation catalyst the alkylation efliuent is passed to a separator wherein a liquid hydrocarbon-rich phase and a liquid hydrogen fluoride-rich phase are formed. The liquid hydrocarbon-rich phase is passed from the separator to a distillation column wherein dissolved hydrogen fluoride is removed as an overhead azeotropic mixture with light hydrocarbons. The bottom fraction contains the alkylate product and also minor proportions of organic fluorine compounds which are undesirable as previously mentioned. In the usual practice the bottom fraction from this distillation is treated to remove the organic fluorine compounds. Such treatments comprise contacting the bottom fraction with a suitable sorption material which selectively sorbs the organic fluorine compounds, or contacting the bottom fraction with a catalytic dehydrofluorination agent which convert the organic fluorine compound to hydrogen fluoride and the corresponding organic radical. Sorption inaterials which have been used to sorb organic fluorine compounds include those known to be catalytically active for hydrogenation and dehydrogenation reactions, such as activated alumina or bauxite. Catalytic dehydrofluorination agents which are suitable for converting the organic fluorine compounds include various fluorides of metals and compounds resulting from treatment of oxides of various metals with hydrogen fluoride. Various other treatments which involve the use of catalytic agents have been used in removing the organic fluorine compounds rendering the hydrocarbon fraction substantially non-corrosive.

In all these treatments it is very difficult, if not impossible, to remove absolutely or even substantially all of the organic fluorine compounds, because in the case of sorbents the sorption power 65 decreases and in the case of catalysts the equilibrium of the decomposition reaction must be considered. As a result of some of the fluorine compounds, especially the high-boiling organic fluorine compounds, remaining in the hydrocarbon fraction, the hydrocarbon stream becomes corrosive as a result of the accumulation of the organic fluorine compounds in the bottom fractions from various fractional distillations subsequent to the conventional organic fluorine compound-removal process. Therefore, it is much to be desired to provide a method for removing substantially all of the organic fluorine compounds from the hydrocarbon stream in order to prevent corrosion of subsequent equipment by concentration of the organic fluorine compounds in the bottom fractions in the variou fractional distillations.

Moreover, since the fluorine combined as the organic fluoride represents over a period of time,

a substantial loss of hydrofluoric acid catalyst in,

a conversion process such as alkylation, the recovery of the fluorine ashydrogen fluoride would amount to a substantial saving in costs of operation and material.

There are other known processes in which gaseous or liquid materials containing minor amounts of organic fluorine compounds are found. and the present invention may be applied to the treatment of such materials or streams. As examples may be mentioned the deliberate formation of organic fluorine compounds, particularlv the low-boiling aliphatic fluorine compounds which are formed by reacting hydrocarbons or chlorinated hydrocarbons with elementary fluorine or hydrogen fluoride under selected conditions. Certain product and residual streams in such processes may carry organically combined fluorine in amounts ranging usually from something less than 50 per cent down to traces.

An object of this invention is to effect substantially complete removal of organically combined fluorine from mixtures containing the same.

Another object of the invention is to provide a new and improved defluorination catalyst.

Another object is to provide a catalyst useful in effecting various organic conversions.

-A further object of the invention is to provide a novel method for the preparation of catalysts.

Yet another object of the invention is to decompose organic fluorides to form hydrogen fluoride, which may be subsequently recovered.

A further obect is to provide an improved process for obtaining a substantially fluorinefree alkylate from a process for the alkylation of low-boiling hydrocarbons in the presence of a fluorine-containing alkylation catalyst.

Another obiect of this invention is to recover fluorine combined as organic fluorine com pounds, which are by-products of an alkylation process, as free hydrogen fluoride to be recycled Further obiects and advantages of the inven-v tion will be apparent to one skilled in the art, from the accompanying disclosure and discussion.

In accordance with certain aspects of this invention, fluorine compounds can be substantially removed from a fluid mixture containing the. same by contacting the fluid mixture with a novel catalytic agent which decomposes the fluorine compound to liberate hydrogen fluoride and with a suitable sorption medium which is capable of sorbing the liberated hydrogen fluoride. In contacting an organic mixture containing an organic fluorine compound with a catalytic agent according to one embodiment of this invention, the organic fluorine compound is decomposed into hydrogen fluoride and the corresponding organic radical. The decomposition of the organic fluorine compound is an equilibrium reaction, as evidenced by the following typical reaction equation:

Once such an equilibrium is established in the presence of a catalyst no further decomposition of the organic fluorine compound takes place unless one of the products of decomposition is removed, such as the olefin or the hydrogen fluoride. If one or both of the decomposition products are removed, the decomposition reaction of the organic fluorine compound will proceed toward completion and thus decompose substantially all of the organic fluorine compound. Consequently, the organic mixture containing the organic fluorine compound is contacted either simultaneously or alternately with the novel catalytic defluorination agent of the in-' vention and with a suitable sorption medium. The removal of the hydrogen fluoride by the sorption medium upsets the decomposition equilibrium and permits further catalytic decomposition of the ,organic fluorine compound.

I have found that catalysts effective for dehydrofluorinations' and other conversions, having unusually high activity and long life, are obtained if certain metals (if necessary having a coating of metal compound reactible with acid) are treated with a strong inorganic oxygen-containing acid whose anhydride is relatively nonvolatile, particularly phosphoric acid, preferably followed by heating the resulting material at elevated temperatures. The preferred metal is a1uminum;' cadmium, zinc, and copper may, however, be used if desired, with especially good results. Any of the metals from magnesium to silver, both inclusive, in the Electromotive Force Series of Elements as compiled by Giles B. Cooke,- Handbook of Chemistry and Physics, Chemical Rubber Publishing C0,, 30th edition (1947'), page 1439, may be employed. The preferred group of metals is composed of those from aluminum to trivalent iron, both inclusive, all of which are above H2, in said Electromotive Force Series, viz. Al, Be, U, Mn, Zn, Cr, Ga, Cd, In, Tl, Co, Ni, Sn, Pb, and Fe. However, the metals mentioned specifically hereinabove, viz. aluminum, cadmium, zinc and copper, are preferred. Of course the elements Te, S, H2, As, 02, and I2 appearing within the named groups in said series are not included in the scope of this invention, being non-metals. The treated metals are preferably used in a relatively flne state of division, such as shot, shavings, filings, short pieces of wire, powder, etc. In case powdered material is used it is suspended in the liquid or gaseous hydrocarbon material to be treated, in accordance with techniques analogous to those utilized in the art of fluid catalytic cracking. Furthermore, mixtures of two or more metals as disclosed in my copending application Serial No. 637,169, filed December 26, 1945, now Patent No. 2,481,208, may be treated with phosphoric or other acid 01' the class described and employed in accordance with the invention. The phosphoric acid used in treating the metal or metals preferably has an acidity (H3PO4) of at least 75 per cent, and more preferably, approximately 85 per cent. Other suitable acids are the various oxygen-containing acids of phosphorus, for instance metaphosphoric or phosphorous acids; also, chromic acid and tungstic acid may be employed.

In accordance with a preferred embodiment of the invention, the catalyst is prepared by immersing the metal in orthophosphoric acid or by otherwise treating the metal with the acid, for example spraying the acid on the metal. After the initial liberation of hydrogen has substantially ceased, the metal together with the material deposited thereon is separated from any excess acid without washing. Preferably the thustreated material is next heated at elevated temperatures, for example 500 to 700 F., for a period of time which may conveniently range from 0.5 to 2 hours. After adjustment of the particle size to the desired value, which is frequently about 5 to mesh, the catalyst is ready for use. This catalyst is probably corrposed of the free metal,

the metal phosphate in the form of pyrophosphate, and P205.

In reacting the metal with the acid, magnesium will be found so active that it is diflicult to stop the reaction and retain some free metal. The metals below hydrogen in the electromotive force series do not react directly with the acid, hence a pre-treatment of same to form a coating reactive with acid is required. This usually comprises treatment with an oxidizing agent. For example, hot chlorine gas will oxidize the metal surface and form the chloride, which is readily reactive with phosphoric acid and the like. Either free oxygen, preferably in the form of air, or a nitrogen oxide compound such as heated N02 or HNOa vapor, is suitable, giving the metal oxide, or sometimes the nitrate, as coating. The thus-treated particles of metal are then reacted with one of the strong inorganic oxygen-containing acids having a relatively non-volatile anhydride and the treatment continued as described to form the finished catalyst. Silver metal usually requires a catalyst or intermediate compound formation for conversion to the oxidized form; thus, silver may be treated with oxygen in the presence of a peroxide, or with hydrogen sulfide to form silver sulfide followed by oxygen treatment to form the oxide. Certain metals above hydrogen in the electromot-ive force series. especially cadmium and lead react with oxygen-containing acids only very slowly, and this reaction may be accelerated to practical rate by adding a trace of another metal, such as copper or copper sulfate or a metal such as platinum or other metal to set up a galvanic cell. After visible'evolution of hydrogen ceases the excess acid is drained and the material calcined as described above.

Other catalysts are prepared by eifecting admixture of the metal directly with the acid anhydride, with or without the salt of the metal and acid. For example, phosphorus pentoxide is sublimed onto particles of spongy zinc. As another example, chromic acid is mixed with iron chromate, the mixture calcined and powdered and admixed with powdered iron metal.

In the preferred embodiment of the present invention, an organic mixture containing an organic fluorine compound is passed, in either the liquid or vapor phase, through a treating zone containing both a powdered or a granular cata- 6 lytic defluorination material and a hydrogen fluoride-sorption medium. This treating zone is usually arranged in such a manner that the catalyst and the sorption medium are in alternate layers. By such an arrangement the flrst catalytic layer establishes a decomposition equilibrium reaction and the subsequent sorption layer upsets this equilibrium by removing liberated hydrogen fluoride; then the next catalytic layer reestablishes the decomposition equilibrium by decomposing at least a portion of the remaining organic fluorine compound. Each following catalytic and sorption layer acts in a similar manner until substantially all of the organic fluorine compound is decomposed.

Another embodiment, which may also be practiced, is the arrangement of the catalyst and sorption medium in successive zones rather than in a single zone; thus, the catalyst will be main--' tained in one separate zone or column and the sorption medium will be maintained in a second and successive zone or column, throuzh which the organic mixture passes, respectively. Still another arrangement may be followed by supporting alternate layers of catalyst and sorption medium in a sorption column in such a manner that free space exists between the supported layers. This arrangement is especially desirable since the tendency for channelling of a liquid hydrocarbon stream through the powdered or granular contact material is minimized. The number of layers or zones which will be suitable for removal of the organic fluorine compound depends upon several factors such as the type of catalytic material, the type of sorption medium,

the conditions of temperature and pressure, and the depth of the catalytic and sorption beds; but such conditions and the number of successive layers or zones may be easily determined by trial. In general, it will be suiiicient to use layers of catalyst and of sorption material about 3 to 6 inches in depth when from about 10 to about 25 total layers are used in the treating zone.

In a somewhat less preferred embodiment of the present invention the catalyst and sorption medium may be admixed together in a treating zone in a more or less uniform manner and the organic mixture contacted with the uniform mixture of catalyst and sorption medium. The arrangement of alternate layers of separate zones for each contact material is preferred in order to facilitate recovery of the sorbed hydrogen fluoride, if desired, and also since the contact of liberated hydrogen fluoride with the catalyst may substantially decrease the catalytic activity thereof by the conversion of the hydrogen fluoride to the corresponding metallic fluoride. Such conversion to the metallic fluoride consumes both the catalyst and the hydrogen fluoride so as to decrease the activity of the catalyst and hinder the recovery of hydrogen fluoride.

The acid-treated metals of the present invention are particularly adaptable to the process disclosed herein in which a fluid containing fluorine compounds is contacted alternately or simultaneously with a defluorination agent and with a hydrogen fluoride sorption material, inasmuch as the acid-treated metal quickly establishes the decomposition equilibrium of the fluorine compounds due to its exceptionally high catalytic activity for the dehydrofluorination reaction.

Sorption materials which have been found suitable for selectively sorbing hydrogen fluoride from an organic mixture have been found to veonmri e;.1mr 1;.- len l lanmetai oxidessuch as alumina,.rchr'omium ox- ,ide -fand. dehydrated metal oxide fgels and the like. Materials which areicapable; oi .sorbing hy I w dragon-fluoride and which involvea'chemical reaction ,to arm a 'decompojsable saltjare especially. Y- able .-i Such sorbentmaterials may comprise; flnorides,of;.the alkali and alkali' earth 'metals, "such-J as-sodium fluoride orpo tas'sium fluoride,- whichl form the additionzcompoun'd,ot-the type :NaEHFL. Ii'des'ired; the "hydro'genffluoride may I be recovered "fromth'e double's'altby heating directly'. or bypassing 'hotxgases over the sorption' medium; Nitrogenbases a'ndgmetal salts that form acid fluorides are also layers, the thickness 'otthe layers/maybe from about} to aboutz's inches and the, number of' layers may' be about loi toabout 2 5-;!the actual thickness. and number. of layers will depend upon .1' the conditions of operation and upon the par-s umns somewhat ditfererit conditionsio'fvtemperyature', pressure; etc; maybehsed foreachcol-r f 'umn during defluorinatiomQ Imus-relatively high The sorb ydra ted bauxite, granu- V I suitablel'or sorption of the liberated hydrogen'fluoride.

ObviouslyEboth the: catalyst 'andsorption medium'mayl'be supported [on warious inert .ma-, terialswell known to those skilled in-thela'rtwithout "departingffrom the. scope or. this invention. Inpra'cticing thepreferred embodinient oi' this invention tor the removal.fof jorganic; ,fluorine compounds from a" predominately hydrocarbon j eati 1a is from about 70 to-about 4009: F.-orihi gher, preferably about 1 75 to aboutf-350. v *sui'e' is from about-110 Qtbi'aboii ,600Qpoundsper mixture; the temperature of th and the pres},

square inch gaga p ere as y rrom: about 200w about 450 pounds per square -inch"g'a'g'e.f f A suit able space velocity in liquidvolurnestoij organic 3 mixture per volume or catalyst per hour is' from about 0.5 to about '10, andpreifera'bly fromabout 2 to about 5. {As previously described; it the,

catalyst and 'sorption medium are arranged in ticullar catalyst and sorption inedi m'use d., Such",

conditions set forth abovefJare'; riot-limiting to, the scope of this invention,- but; arethosewhmh; have been found preferable-ingeneral-Pierre moving substantially'all of the'organic "flno'rin' coi'npouncis from the hydrocarbon {mixture-with: ut efiecting extensive chemical changes intheahydrocarbons themselves. Various other ,condi- I --tions may be found appropriate-byitrial.

A ln the case where the catalyticfl-a'gentf and the sorption' medium are infseparate z'one'sfor-coltemperatures and low pressures' m'aybe used-in the catalyst,'zone, while relativelylow temp'era tures and high pressures maybe usedin the 'sorp- .tion zone. Howeverf'dueto-eeonomic reasons-it j ,vfmayfbef rlnbre desirable ,to '-maintain substantially f ine; 'co iditions in both the -"catalyti c and vent zone. In case the sorption medium is a nonreactive material which sorbs the liberated hydrogen fluoride, such as bauxite or charcoal, this material'may be regenerated by passing superheated steam orother hot gases, such as butane, at atemperature from about 400 to about 800 F.,

preferably about 500 to 600 F., and at approximately atmospheric pressure through or in contact with the sorption medium. When a material, such as sodium or potassium fluoride, which forms an additive compound with the liberated hydrogen fluoride, is used as the sorption medium, the temperature of the regenerating gas,- such as air, steam, butane, etc., is from about 500 to'about .1000 F., preferably from about600 ,to'about 70051 1, and the pressure is.

approximately atmospheric. It may be preferred tov operate the regeneration cycle at the same pressure as the sorption cycle, and thus the use i '20 of elevated pressure for regeneration is within thescope of this invention; Regeneration of the {heating the sorption medium during regeneration, whether by direct means'jor'by'the use of hotgases, yapo'ro'us hydrogen fluoride is liberfated: which maybe. recovered iby methods fa! miliar to those skilled the art. In particular,

when a regenerating gas, such asbutane, is used,

I thejresulting aseous mixture .by condensing the gaseous 'mixture and iractionally distilling the condensate torecover. the. hydrogenrfiuoride.

either organic or inorganic fluorine compounds fromlboth organic and inorganic fluid mixtures, particular benefits of it have been realized in con- 40 vention in com Process.

ection with such an alkylation fsuch olefincontaining fractions are shown in the following table: I

. g V LiquidVolurnePerCentn Component Q 1 I A.B C' 1D E F "(is .012 --'0.5' 10.6 '0'. 9.6 8.1 1. 9 35.1 30.7 =33, "16'56 24.9 20.0 17.0 17.3 s. 22.4 428.2 --22.1 34.4 37.9 35. 13.7913 15.0 as 5.0 36.5: '24s 33.9 0.4- 0.1 ,0.3 v 3.2 as 19. fioep- :0 ,-10o.0g10o.o 100.0 100.

1| liquid-hydrogen fluoride, isintroduced into line 'i'gsorption"mediumjmay be accomplished also-by .l ieating' the"sorption medium directly without passing a hot gas through th'ejmedium; Upon the hydrogen-fluoride maybe recovered from Although this invention can-be applied with'advantage in many modifications to the removal of,

nection with the alkylation of low-boiling isoparaflinswith low-boiling olefins in the presence of ,a fluorine-containing alkylation catalyst. "It is' believed that the principles of this invention, [may beadequately illustrated by the discussion of "specific modifications in connection with the ac companyingi drawings; in which Figures 1 ,2, and

3 illustrate diagrammatically -various arrange-- merits of apparatus elements a'ndflow of materials therethrough suitable for-practicing this 'in- Referring to Figure 1, 9. suitable alkylation reac-.

ment1.,Analkylationfeed, comprising an isoparv r -aflin andan olefin, is charged to re'actor I through v .lineG. Such a ,feed may comprise isobutane and a butane-butylene fraction. ."ori a; butene-amylene ffraction" from ,a reflnery Typical examples of -,hydroiluor1c acidalkylation 'catal ystsuch as V I9 and the feed and catalyst may pass either together or separately into reactor 1, as desired. Generally the temperature of alkylation will be about 80 to about 100 F., and sufficient pressure will exist in reactor I to maintain the reactants in liquid phase. A hydrocarbon to acid ratio between about 0.5:1 and about 2:1' is preferred to obtain the appropriate alkylation of the isoparaflin. The ratio of isoparaflin to olefin in the reaction zone itself will be much larger than the ratio of isoparaffln to olefin in the feed. The high ratio of isoparaflln to-olefln is accomplished in part by recirculating a portion of the isoparaflin in the reaction zone; usually the ratio of isoparaffln to olefln in the reaction zone itself is 100:1 or higher.

From reactor 1 the resulting hydrocarbon alkylation eflluent passes to separator 9 through line 8. In separator 9 a liquid hydrocarbon-rich phase is separated from a heavier liquid hydrogen fluoride-rich phase by gravity. The hydrogen fluoride-rich phase is withdrawn from separator 9 through line H and may be passed to a puriflcation system (not shown) for removal of acidsoluble oils and water. After purification the hydrogen fluoride is returned to reactor I as a catalyst. If desired, all or a portion of the hydrogen fluoride-richphase may be passed directly from separator 9 through lines I I, I2 and I3 to reactor 1. Makeup or fresh hydrogen fluoride is introduced into the system through line IS.

The hydrocarbon-rich phase from separator 9 contains some dissolved hydrogen fluoride and is therefore passed to an azeotropic distillation column l6 through line H .to remove the hydrogen fluoride as an overhead product from the distillation zone. An azeotropic mixture of hydrogen fluoride and low-boiling hydrocarbons is removed from azeotrope column I6 through line l1 and passed through condenser l8 thence into separator 9 where it separates into a hydrocarbon-rich phase and a hydrogen fluoride-rich phase. The low-boiling hydrocarbons in the azeotropic mixture comprise propane, ethane, and some butanes. The bottom fraction from azeotrope column l6 comprises essentially unreacted isobutane, alkylate, some propane, and minor Proportions of organically combined fluorine present as a by-product of the alkylation reaction. The organically combined fluorine comprises C4 fluorides and lighter organic fluorides and lesser proportions of organic fluorine compounds heavier than C4 fluorides.

lower portion of azeotrope column It, as shown by numeral IS. The liquid bottom product of the distillation containing the organic fluorine compounds contacts the defluorination catalyst l at the kettle temperature of the distillation under conditions such that the organic fluorine compounds are decomposed within column l6 itself to form hydrogen fluoride and the corresponding organic radical. The free hydrogen fluoride liberated in the lower portion of column I6 by the defluorination catalyst therein passes from column IS with the vaporous overhead product through line H. The liquid bottom fraction removed from column l6 through line 2lis substantially free from organic fluorine compounds. A portion of this bottom fraction, when it still contains some organic fluorine compounds, may

be recycled through line 20 to the lower portion of the azeotrope column I 6 for further contact with the defluorination catalyst 15, if desired.

Defluorination catalyst l5 may be placed in any desired position in azeotrope column l6; however, to prevent extensive contact of free hydrogen fluoride with the catalyst and to obtain maximum temperature of contact, the catalyst is positioned in the lower portion of column l6, as shown.

In another modification, with or without the presence of defluorination catalyst IS in azeotrope column Hi, the bottom fraction is passed from azeotrope column l6 through line 2| to a treating unit 23 for removal of these organic fluorine compounds or a portion thereof. Treating unit 23 may comprise a single zone with alternate layers of an active defluorination catalyst and a selective sorption medium as previously discussed and shown in Figure 2. Treating unit 23, on the other hand, may also be a series of successive columns alternately containing an active defluorination catalyst and a sorption medium, as indicated in Figure 3. The quantity of organic fluorine in the bottom fraction from column l6, which passes to treating unit 23, is in general not more than about 0.1 per cent by weight of the hydrocarbon stream, and usually not more than about 0.001 to about .05 per cent, when no defluorination catalyst is present in azeotrope column l6.

Generally the operating conditions for removing the organic fluorine compounds in treating unit 23 by the process of this invention are such that the removal is effected in the liquid phase. However, vapor phase operation is within the scope of this invention. Liquid phase operation is preferred because lower temperatures of operation and smaller sized equipment may be used since the hydrocarbon stream is liquid. The use of pressures from about 200 to about 450 pounds per square inch gage temperatures from about 1'75 to about 350 F., is preferred. Using these preferred pressures, a space velocity from about 2 to about 3 liquid volumes of hydrocarbon effluent per volume of catalyst per hour is generally adequate. Although various dehydrofluorination catalysts described herein may be used in carrying out the process of this invention, a particularly effective catalyst, as previously described and which is preferred as the catalytic defluorination agent, comprises particles of aluminum metal which have been treated with concentrated orthophosphoric acid, drained, and heated at an elevated temperature without washing. This active catalyst quickly brings about an equilibrium decomposition reaction of the or.- ganic fluorine compound to liberate free hydrogen fluoride. The particular method of preparing such catalyst is described hereinafter in the examples. Charcoal isa particularly suitable sorption medium and is the preferred sorption medium to be used in treating unit 23. When the bottom fraction of azeotrope column I6 is treated to defluorinate the same, preferably the conditions of operation are such that the C4 fluorides and lighter organic fluorides are re.- moved from the eilluent leaving the heavier organic fluorine compounds in the hydrocarbon stream. These heavier organic fluorine compounds pass through subsequent fractional distillations and are removed with the bottom fractions' of the distillations as hereinafter described. By removing only the C4 and lighter fluorides mild conditions of operation can be used in treatumn s is operated il l' sllch a-. manner-.that om the C4 fluorides .and',:. lighter fluoridesl'arecree is also less tendency. for chemical changes to occur in the organic mixture being treated to remove the organic fluorine compounds. In'op- I crating in this preferred manner, the organic fluorine content of the efllu'ent from treating-f unit 23 is about 0.002 to about 0.001 per cent by A portion ofweight of the resulting eflluent. the efliuent from treatingunit 23 may berecycled through line 26 and in this way the fluorine content may be' decreased even more. If prevferred, however, all or alarge portion of the 1 organic. fluorine compounds may be ,removed I from the hydrocarbon stream by treating unit 23 alone, or in combination with a defiuorination catalyst in azeotrope column [6.

'As previously discussed, the sorption medium may be regenerated and the hydrogen fluoride 'movedff'ro'm the hydrocarbon 'efliuent; the bot-f tom fraction .jflOlIl element 28 is passed through d line 33 andilinef34' to a'treating unitfl'forrthc removal of the' heavyorganic fluorine compounds'fl Treatingunit133- 'isrsimilar 'in-E' arrangement of catalyst sorption medium to {treating .unit' 23 and is operated;.-11n a, similar mannerto unit 23; -but under somewhatfmorfefsevere conditions vsince 'the'heavy jzfluorides have concentrated in v a the high-boiling'fractiom' the percentage of .or-'

:- 'ganicfluorine compounds the hydrocarbon ."stream atthis'point in the process' will be aping a hot gas, such as air, steam, butane, etc.,

through the sorption medium.

In a preferred embodiment of the present invention, th sorp-.

tion medium, such as charcoal, is regenerated by passing butane at a temperature between 1 about 500 and about 600 F. through line 22 into- 1 treating unit 23 and withdrawing a resulting hydrogen fluoride-rich gas from the system through lines 24 and 21.- .The hydrogen fluoride may be separated from the butane in a conventional manner known in the art, such as by fraceflluent of the presentillustrated'process. Since it is necessary to regenerate the sorption mepreciably higher than before removal of the various lower-boiling fractions from the hydro- ;carbon .eflluent infr'actionation system 28. However, after. being treated'in treater 36, the resulting hydrocarbon 7 stream 1 will usually contain not more thanj"about'.0.005 per cent organic fluo- '20 recovered therefrom by direct heating or by pass- 1 If thejlight alkylateproduct removed through line 4| contains appreciable amounts of organic fluorine compounds which have as yet not been removed by previoust'r'eating steps, this light alkylate may beffreed of such organic fluorine compounds vby passing the alkylate overhead through line 42 and treating unit 43 which is also 1 similar treating unit 23. The conditions. of v V operationgfor treating-unit 43 are alsosimilar to those conditions of operation for treating unit 23. As a result of the treatment of-the hydrocarbjonstr'eamfthe light-'alkylate will contain not more thanabout 0.0006 to about 0.0005 per dium after a certain period of use, it will often be desirable to have several units for removing organic fluorine compounds in parallel so that while one unit is in process flow, another unit may be regenerated; thus, a continuous flow process is possible. If desired, therefore, treating unit 23 may comprise several units in-parallel for removing organic fluorine compounds.-

Fromtreating unit 23 the resulting efiiuent passes through line 24 to fractionation system 23. Fractionation system 28 may comprise a tively. 40

series of fractional distillation columns for the e separation of the various components of the through line :29 toberecycled to reactor '1 asra,

portion of the feed thereto. ,Propaneand lighter hydrocarbons which are separated from the, heavier hydrocarbons may be removed from sys 3 tem 28 through line. a Normal butane which;

is also separated from other hydrocarbons is removed from fractionationsystem 28 through line 32. The normalibutane may be recoveredasa} product or may be isomerized' (not'shown) to. isobutane and passed to reactor l'as a portion of the feed; A- relatively high-boiling fraction V v from system 28 comprising the alkylate product is passed to. another fra'ctionating column for, the separation "of light alkylate'-..fromq.'heavy. alkylate. This'high bo'iling fractionfrom fractionation system 28 is"thus-passedthroughjline cent organic fluorine by weight. 7

Both treating units 36 {and 43 may be-regeneratedby purging themgwith a hot gas as previously described, the hotv gases being passed through the treating 35 and 43 by means of lines 31and38, and lines and 42, respecinthe alkylation system by the presence of pro- 5 pane and lighter hydrocarbons in .the alkylation 1 effluent, a small ,portion'of these hydrocarbons may be vented from the system through line l9. 4 ln-theoperation ofsuch an alkylation system it is'no't necessary in all cases to have three treating units as shown in Figurel, especially if'adefluorination catalyst is presentin' azeo trope column I6. Treating junit23lalone maybe 'sufiicient to. remove 'the desi'redamount of 'organic fluorine compounds; on the. other; hand,

in' some cases treating -unit 23 may be' omitted andtreating units'35and431used instead; Where. r

onlyqa smallamount of organic fluorine com where" "these :3 to'fractionator 40.1 A light alkyla'tel-isre-i l' is removed through line 39, as a byproduct y j. when treating unit 23 and/or azeotrope colpounds present inthe? hydrocarbon eiiluent- :j

heavierthaniC;fluoridesyitmaybe' suflicient to Q '-i f i .g 1 1 s i I0 h n IthelightfaIkyIate productwithout" previous" treatam. F h' h r bon'e eti e uent v seen,- therefore,.-that treating}units-inlay bej j leje -ir a ousv po itio f the prqc ss; dependinguponi the requ men he; presence of a defluorinatio 'catalyst in.columnlit ma be 5 gsuflicient alone toremove the 'desired quantity of organicfluorine compounds;

'1 Figure :2 diagrammatically 'repres'ents 'apparams for an: embodiment; of treating/unit '23, in a .which' iigure -is.shownfalternate layers of de-' fluorination' catalys't andisorptionmedium. The "hydrocarbon eliluent-enters treating .unit 23 'fthrough'linejl v VA qrtion of-theresultirigieflliient'maybe recycled i-throl'lg hlinef'zi 'iNllmeralfl of Figure-21 desiz and: i's-rernoved' through line 24.;

1 To prevent th e'build up of excessive" pressure hates successive layers of a defluorination cata-- lyst, and numeral 54 designates successive layers of a sorption medium for sorbing and removing liberated hydrogen fluoride.

Figure 3 diagrammatically represents another arrangement of apparatus for treating unit 23 in whichthe defluorination catalyst and sorption medium are contained in separate columns. The hydrocarbon eiiiuent passes through line 2i into column 1 I, which contains a defluorination catalyst designated by numeral 12. The treated hydrocarbon eiliuent is withdrawn from column ll through line 13 and is introduced into a second column 14 which contains a sorption medium designated by numeral 16 for removing liberated hydrogen fluoride. The eflluent from column 14 is removed by line 11 and a portion thereof may be recycled to column H through line 18. The eflluent from column I4 is passed to column 19 which contains a defluorination catalyst, and the resulting eflluent is removed therefrom through line 8|. The effluent from column 19 is placed in a beaker and covered with 85 per cent orthophosphoric acid. When evolution of hydrogen had apparently ceased, the solid material was removed from the beaker, and the particles were broken to approximately the size of the original shavings. The solid material was then placed in an electrically heated steel tube in which it was slowly heated to 625 F. and maintained at thi temperature for one hour. It was then removed, cooled, and reduced to a particle size sufliciently small to pass an 8-mesh screen.

Dehydrofluorination data obtained by the use of this catalyst are given in Example II.

EXAMPLEII Hydrogen fluoride-free hydrocarbon eiiiuent from a hydrofluoric acid alkylation unit, in which isobutane was alkylated with butylenes, was contacted at 250 F. and 400 p. s. i. in a continuous flow system with the catalyst prepared as described in Example I. The data obtained are given in Table I.

TABLE I Dehydrofiuorination with phosphoricacid- I treated aluminum 0 l S F Compounds, Weight Per Cent umu aace fig tive Vol. Ve ocity, F a Time Tr\e at1ed/ liq]. vol./ Before Treatment After Treatment g;

o v0 cat- Hour Catalyst alyst/br. Cent Org. F HF Org. F HF 51 186 4. l 0. 03 18 0. 0000 0. 0009 0. 0014 97 167 455 4. 1 0. 0265 0. 0000 0. 0059 0. 0056 78 220 600 l. 9 0. 0288 0- 0032 0. 0067 0.0193 77 339 781 3. 6 0. 0227 0. 0051 0. 0069 0. 0141 70 523 l, 180 l. 8 0. 0184 0. 0003 0. 0070 0. 0090 62 592 1, 345 3. 0 0. 0209 0. 0000 0. 0078 0. 0096 63 passed to column 82 which contains a sorption EXAMPLE 111 medium. The eflluent from column 82 is removed by line 24 and a portion thereof may be recycled to column 19 through line 83. Any number of successive columns of defluorination catalyst and sorption medium may be used; the number of columns will depend upon the requirements necessary for removing the desired amount of or- TABLE II Dehudrofluormatzon with etched alummum F Weight Per Cent Cumula- S ace Cumulative Vol. Ve ocity. a tive Treated] liq. vol./ Before Treatment After Treatment g, Time, Vol. vol. cat- C Hour Catalyst alyst/hr. en

Org. F HF Org. F HF EXAMPLE I Aluminum shavings about 0.005 inch thick were Comparison of the data in Tables I and II clearly shows the superiority of phosphoric acidtreated aluminum as a catalyst for removal of organic fluorine. The etched aluminum, after treatment of 1340 volumes of hydrocarbon containing organic fluorine, removed only 17 per cent of the organic fluorine, whereas, after treatment of 1345 volumes, the phosphoric acid-treated aluminum removed 63 per cent. It will also be noted that at the end of each run the etched aluminum metal had only a little less than a third of its original activity, that is it was remov- 76 ing 1': per cent fluorine, whereas at the start it removed 55 per cent fluorine, while the phosphoric acid-treated aluminum metal retained sixty per cent of its original activity. Further comparison shows that in the eased the phosphoric acid-treated catalyst, after treatment of 455 volumes of feed at 4.1 space velocity, the fluorine removal was 78 per cent, whereas in the case of the HCl-etched aluminum after treatment of 497 volumes of feed at 1.1 to 2.5 space velocitythe latter catalyst was removing only about 23 per cent of the organic fluorine.

Although the data shown in Table II were ob- I tained at 212 F., whereas the data presented in Table I were obtained at 250 F., experience has shown that an increase of temperature from 212 to 250 F. does not give a significant increase in fluorine removal. Therefore the temperatures of the two runs which are compared are of the same order insofar as the effect on rapidity and extent of fluorine removal are concerned.

This is further borne out in Example IV. Like-j wise, the lower pressure employed in Example III as compared with that in Example II did not significantly afiect the result- .EXAMPLEIV Dehydrofluorination with etched aluminum and at superatmospheric pressures preferably from 200 to 1000 pounds per square inch. Flow rates are chosen to give the desired extent of polymerization, and generally range from 1 to 10 liquid volumes feed per volume of catalyst per hour or to 6000 volumes of gas per volume of catalyst per hour. The reaction mixture may consist of a single pure olefin or a mixture of olefins, but will preferably also contain inert diluents such as light paraflin hydrocarbons. A mixture of isobutylene with normal butylenes and butane may be subjected to co-polymerization, for example. A somewhat related operation involves the stabilization of a cracked gasoline against gum formation by treatment with my catalysts at 100 to 300 F. and 0 to 300 p. s. i., effecting polymerization of diolefins and other highly unsaturated materials while leaving the desired mono-olefins relatively unaifected.

The alkylation of aromatic hydrocarbons may also be effected, employing the catalysts of the present invention. Thus, benzene, toluene or naphthalene may be reacted with a methylating agent. such as methyl alcohol or dimethyl ether at300 to 500 C. and a pressure of 1 to 300 atmospheres with a contact time which will vary from 1 to 100 minutes, depending upon the temperature and other reaction conditions, the longer contact times being employed with the lower temperature and vice-versa. At least one mol of the aromatic hydrocarbon per'mol of methylating agent should be. employed, and preferably the former is in considerable excess over thelatter. other alkylating agents, particularly ethylene C l s F Weight Per Cent umu apace g g tive Vol. Velocity, jgs Treated/ liq. vol./ Before Treatment After Treatment P gg Vol. vol. cat- 082';

"- Catalyst alyst/hr.

Org. F HF Org. F' HF Although this invention has been described with reference .to alkylation in particular, and the examples have used particular catalysts, it is evident that the invention in general 'may be used in connection with various other processes and higher olefins, are effective to produce the corresponding alkyl'ated aromatic hydrocarbons. The mono-alkyl derivative is formed to the greatest extent although diand higher poly-alkyl for the removal of fluorine compounds from a 55 fluid mixture. Furthermore, various modifications of equipment, process flow, and specific catalysts and the preparation thereof, will be obvious to those skilled in the art without departing from the scope of this invention.

The methods disclosed herein may be employed in the preparation of catalysts which are particularly adapted for use in the defluorinating of organic materials as describedabove. However, the catalysts of this invention are likewise adaptable to use in various other chemical reactions, particularly those catalyzed by phosphorus pentoxide and/or metal phosphates including pyrophosphates, such as polymerization of unsaturated hydrocarbons, and others described hereinbelow.

derivatives are present in the reaction mixture to some extent, and may be made the predominant product if desired byincreasing the contact time Unsaturated hydrocarbons, particularly the C2 and/or decreasing the ratio of aromatic hydrocarbon to alkylating agent. As part of the same over-all process to form mono-alkyl aromatics, or

as-a separate process, polyalkyl aromatic hydrocarbons may be dealkylated by reaction with benzene or other aromatic whereby alkyl groups are transferred from the polyalkyl aromatics to the latter. Preferably at least. one mol of henzene per mol of poly-alkyl aromatic is employed and this" quantity may range up to 10 mols per mol of poly-alkyl aromatic; temperatures of 300 to 600. C. and pressures of l to 200 atmospheres are suitable.

Other processes in which my catalysts find particular utility is in the dehydration of alcohols to'form' the corresponding olefins, in-which an alcohol, preferably having from 2 to 5 carbon atoms per molecule, is contacted with the catalyst at 300 to 500 C. at about atmospheric pressure,

employinga liquid space velocity from 1 to 25 volumes per volume of catalyst per hour. Conversely, oleflns are hydrated to form the corresion per pass desired, as well as the activity of the particular catalyst employed.

As another example of the utility of the catalysts of this invention, methane may be utilized to form methanol and formaldehyde as principal reaction products, by passing oxygen admixed with a molar excess of methane over the catalyst at 600 to 1000 F. at a pressure of 200 to 750 pounds per square inch.

In any of the foregoing conversion processes in which the catalyst becomes deactivated by deposition of carbonaceous material thereon, effective reactivation of the catalyst may be accomplished by stopping the fiow of reactants thereover and passing an oxygen-containing gas through the catalyst mass at conditions of oxygen concentration and flow rate controlled to avoid excessive temperature in the catalyst whereby the carbonaceous matter is removed from the catalyst by oxidation and the catalyst put in condition for reuse. Other specific uses of the catalyst described and claimed herein will be apparent to one skilled in the art.

I claim:

1. A process for treating an organic material to remove organically combined fluorine there from, which comprises subjecting an organic material containing organically combined fluorine to the action of a defluorinating catalyst comprising at least one metal between magnesium and silver, both inclusive, in the electromotive force series admixed with a material obtained by calcining a mixture of a strong inorganic acid having a relatively non-volatile anhydride and the reaction product of said metal with said acid, which catalyst is active under the conditions of treatment in efiecting decomposition of organic fluorine compounds.

2. The process of claim 1 in which said defluorinating catalyst comprises a mixture of aluminum, an aluminum phosphate and phosphorus pentoxide. 3. The process of claim 1 in which said defluorinating catalyst comprises particles of zinc treated with an excess of a liquid oxygen-containing acid of phosphorus and then calcined.

4. The process of claim 1 in which said strong inorganic acid is chromic acid.

5. The process of claim 1 in which said defluorinating catalyst comprises particles of aluminum treated with excess orthophosphoric acid and then calcined, without intermediate washing, at a temperature within the range of about 500 F. to about 700 F.

6. A process for treating an organic material to remove organically combined fluorine therefrom, which comprises subjecting an organic material containing organically combined fluorine to the action of a defluorinating catalyst comprising an intimate admixture of a metal below magnesium and above hydrogen in the electromotive force series with a relatively nonvolatile anhydride of a strong inorganic acid, which catalyst is active under the conditions of treatment in effecting decomposition of organic fluorine compounds.

'7. The process of claim 6 in which said relatively non-volatile anhydride of a strong inorganic acid is phosphorus pentoxide.

8. The process of claim 6 in which said catalyst comprises particles of said metal treated with an excess of a liquid strong inorganic acid having a relatively non-volatile anhydride under conditions eifecting reaction between said acid and the surface of said particles until visible evolution of hydrogen subsides, followed by separating the bulk of the excess acid so that the particles retain some residual acid, and calcining the resulting particles to i'orm said catalyst.

9. A process for treating a mixture containing a major proportion of hydrocarbons to remove organically combined fluorine, therefrom, which comprises distilling said mixture in the presence of a defiuorination catalyst comprising aluminum metal treated with excess phosphoric acid and then calcined without washing, under conditions such that said organically combined fluorine is decomposed to hydrogen fluoride and the corresponding organic radical, removing from said distillation an overhead fraction comprising hydrogen fluoride, and removing from said distillation a bottom fraction comprising hydrocarbons substantially free from organically combined fluorine.

10. In an alkylation process for the alkylation of an alkylatable hydrocarbon with an olefin in the presence of a hydrofluoric acid alkylation catalyst wherein organic fluorine compounds are formed as by-products of said alkylation and contaminate a hydrocarbon alkylation eflluent, the method for removing said organic fluorine compounds which comprises separating said hydrocarbon alkylation eflluent into a liquid hydrocarbon-rich phase and a liquid hydrofluoric acidrich phase, passing said hydrocarbon-rich phase containing dissolved hydrofluoric acid and minor proportions of organic fluorine compounds to a fractional distillation and separating therein a relatively low-boiling fraction comprising substantially all ofsaid dissolved hydrofluoric acid and a relatively high-boiling fraction containing organic fluorine compounds, and subjecting said high-boiling fraction to the action of a defluorination catalyst comprising an intimate admixture of a metal between magnesium and silver,.

both inclusive, in the electromotive force series with a relatively non-volatile anhydride of a strong inorganic acid and the calcined reaction product of said metal with said acid, under conditions such that decomposition of said organic fluorine com ounds is efiected without effecting extensive chemical changes in said high-boiling fraction.

11. In a process for the alkylation of isobutane with an olefin in the presence of a hydrofluoric acid alkylation catalyst wherein organic fluorine compounds are formed as by-products of said alkylation and contaminate a hydrocarbon alkylation eilluent, the method for removing said organic fluorine compounds which comprises separating said hydrocarbon alkylation efiiuent into a liquid hydrocarbon-rich phase and a liquid hydrofluoric acid-rich phase, passing said hydrocarbon-rich phase containing dissolved hydrofluoric acid and minor proportions of organic fluorine compounds to a fractional distillation and separating therein a relatively low-boiling fraction comprising substantially all of said dissolved hydrofluoric acid and a relatively highboiling fraction containing organic fluorine compounds, passing said high-boiling fraction to a treating zone for removal of organic fluorine 4 compounds from said fraction, said treating zone comprising alternate layers of a, defluorination catalyst and a solid hydrogen fluoride sorption medium, said defluorination catalyst comprising particles of aluminum which have been treated with an excess of concentrated orthophosphoric acid and then calcined without intermediate washing at a temperature within the range of about 500 F. to about 700 F., maintaining a temperature between about 175 F. and about 350 F. and a pressure between about 200 and 20 about 450 pounds per square inch gage in said treating zone, maintaining a space velocity in liquid volumes of the said high-boiling fraction passingthrough said treating zone per volume of catalyst per hour between about 2 and about 5, and removing a resulting effluent from said treating zone substantially free from fluorine compounds.

JACK F. EBERLE.

No references cited. 

1. A PROCESS FOR TREATING AN ORGANIC MATERIAL TO REMOVE ORGANICALLY COMBINED FLUORINE THEREFROM, WHICH COMPRISES SUBJECTING AN ORGANIC MATERIAL CONTAINING ORGANICALLY COMBINED FLUORINE TO THE ACTION OF A DEFLUORINATING CATALYST COMPRISING AT LEAST ONE METAL BETWEEN MAGNESIUM AND SILVER, BOTH INCLUSIVE, IN THE ELECTROMOTIVE FORCE SERIES ADMIXED WITH A MATERIAL OBTAINED BY CALCINING A MIXTURE OF A STRONG INORGANIC ACID HAVING A RELATIVELY NON-VOLATILE ANHYDRIDE AND THE REACTION PRODUCT OF SAID METAL WITH SAID ACID, WHICH CATALYST IS ACTIVE UNDER THE CONDITIONS OF TREATMENT IN EFFECTING DECOMPOSITION OF ORGANIC FLUORINE COMPOUNDS. 